The present invention relates to a seal for a heat exchanger, especially for heat exchangers useful in vehicles.
Almost all vehicles such as automobiles, trucks, and busses include heat exchangers for rejecting waste heat back into the ambient surroundings. This waste heat may come directly from the vehicle engine, air conditioning system, transmission, or other heat rejecting systems. In order to manufacture these heat exchangers at a low cost, it is necessary to employ fabrication and assembly techniques that are amenable to a high production rate.
Some vehicle heat exchangers are produced by coupling a lightweight, molded plastic tank to a brazed aluminum header assembly. In some of those heat exchangers an elastomeric o-ring or seal is placed between the tank and header assembly. A force is applied to the tank and header so as to compress the o-ring and while the header and tank are so forced together, tabs on the header are bent against the tank to couple the header and tank together.
Often during the operation of bending the tabs the loads required to bend the tab also distort the channel or groove within which the o-ring has been placed. The operation of bending the tabs thus compresses the o-ring beyond the level of compression achieved prior to the bending operation. The o-ring may be compressed beyond recognized compression limits. Although this over compression may result in an acceptable seal immediately after manufacturing, repeated thermal cycling of the radiator will eventually cause the overcompressed o-ring to crack and leak. In addition, the overcompressed o-ring may experience excessive compression set, such that the o-ring may retract from the adjacent sealing surfaces and cease to seal under cold ambient conditions.
The present invention provides a novel and unobvious method and apparatus for limiting compression of the heat exchanger seal.